INTRODUCTION: The clinical results of arthroscopic capsular release for frozen shoulder in diabetic (group 1) and idiopathic (group 2) patients were compared. Surgery was performed on 28 shoulders of 26 patients (24 women, 2 men) with frozen shoulder unresponsive to conservative treatment. The mean age was 50 (range 40-65). A total of 14 patients were included in group 1, and 12 were in group 2. The average duration of complaints was 10 and 7 months in groups 1 and 2, respectively. The evaluation of shoulder functions was made according to the University of California, Los Angeles (UCLA) and Constant Scoring Systems. Duration of complete pain relief and for regaining range of motion (ROM) after surgery were also noted in their final follow-up examination. RESULTS: The mean follow-up period was 48.5 and 60.2 months in group 1 and group 2, respectively. There was no significant difference between the two groups in terms of the postoperative duration of complete pain relief and that for regaining ROM (P > 0.05). The duration of complete pain relief was 2.6 and 2.5 months, and regaining of ROM was 1.6 and 1.5 months for groups 1 and 2, respectively. The postoperative UCLA and Constant scores had significant increases in both groups compared to the preoperative ones (P < 0.05). There was a significant difference between the groups in terms of Constant scores (P < 0.05) while there was no difference in terms of UCLA scores (P > 0.05). There was a statistically significant difference in shoulder abduction and internal rotation degrees between the groups (P < 0.05). CONCLUSION: The results of arthroscopic capsular release for frozen shoulder in diabetic patients had less good results in terms of range of motion and Constant-Score. There was no significant difference between the two groups in terms of the duration of pain relief and that of regaining the ROM.